5 Answers
5

Gui Method

If you want something to run when a user logs in, the easiest way is to use the GUI. You can

Go to the System Prefs > Accounts > Login Items screen, and add the item there by

clicking the + symbol

dragging and dropping the .app onto the pane

In the dock, bring up the context menu for an app, select Options, then select Open at Login

Launchd method

If you want to launch something that is not a .app, or you want to have more control over launching it, such as:

at a certain time or at a specified interval

continuously re-launching if it crashes

not related to user login

as a function of network access

only run when another process is running

when a file is added to a folder

etc.

then you want to use the technical solution that is launchd.

The easiest way to set up a launchd config file is to use a tool to help. At the time of writing the most popular method is Lingon (which has an older free version available from SourceForge), or the PList Website tool.

Hand Coding

If you don't want to use Lingon or the PList Website and only want to use the raw tools available on the system, you can write your own launchdplist by hand

Here is my launchd script to run SomeApp continuously after the system boots (independent of a user logging in). It is in /System/Library/LaunchAgents/ and called SomeApp.restart.plist. If it is run based on a user login, it could be stored in ~/Library/LaunchAgents/

Huh ? Are you sure about that ? It says in the UI of your screenshot "These items will open automatically when you log in" - isn't that different from when the system boots ? Also, your link seems to 404.
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sscFeb 17 at 9:37

So the script in the code block should be saved as /path/to/script, and sudo defaults write com.apple.loginwindow LoginHook /path/to/script? And the point in running a script in the home directory is that each user can have a custom (or no) ~/.loginhook?
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ؘؘؘؘAug 6 '11 at 13:44

@Lri - yes, precisely. Sorry that wasn't clearer. The block code could be /usr/local/bin/loginhook.sh and, since it is run by root, it will look for a $HOME/.loginhook when a user logs in, and run it as that user.
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TJ LuomaAug 6 '11 at 22:18

Running an app at a specified time can be done easily in iCal, as I have just found out thanks to another forum!

Make a new event in iCal for the time you want the app to open.

At 'Alert' choose 'Open File' - so, you can set a file to open, which will obviously also open the default application for that file type.

To just open an app, rather than a file, change the 'iCal' dropdown to 'Other...' and choose the app you want to run!

One thing to be aware of is that if you have multiple Macs sharing stuff over iCloud, this event will also run on those apps, which you may or may not want.
To make this only happen on a single Mac, you need to create the event in an 'On My Mac' calendar which you can do as follows...

Hide all other iCloud or shared calendars on the left hand bar by hovering over the calendar name and clicking the 'hide' button which will appear.

Now right click (or Option click if you're a complete cretin and still haven't realised that you have more than one finger and can change your mouse preferences so that it is slightly more useful than its default 'cretinous brick for cretins' state) and choose 'New Calendar'.

Because all shared calendars are hidden, this new calendar will be created as 'On My Mac' and will be local to this Mac.

I've only just found this out myself, and was pleasantly suprised by both tips, so thought I'd share them here.

I got the info from these helpful people over here...so thanks you people!...